The information processing industry as well as the audio and video recording industry is expanding at an extremely high rate as is well known. In fact, in the 1982 Annual Report of IBM, it is predicted that the information processing industry will exceed $1 trillion by 1990. In this prediction, computer-related hardware is forecast to be a $200 billion segment of the industry. Of this segment, the rigid disk drive portion is the single, largest element. It is further forecast that the rigid disk market will grow from an $11 billion businesses in 1983 to well over $40 billion dollars by 1990.
By 1990 it is forecase that a disk platter used in information storage devices will have up to 50 times the storage capacity of a Winchester Hard Disk shipped in 1985 and will cost less than floppy disks. Speed will be equal to or faster than anything the computer world has enjoyed and will have a reliability factor so high hat backup can become essentially redundant.
Stereo systems will employ the exact same type of disk. A user may accidentally drop the audio disk on the floor and in haste to pick it up, may step on it then wipe it with a wet rag and dry it with a napkin. He then may put it back in the disk player and continue with not a worry about a scratch. Users will be able to enjoy music, watch a movie on TV or they can record right over existing audio, video or data.
The future as described is not far away. By the late 1990's this type of storage device and playback unit could be in every home and/or business in the industrialized world.
Optical disks are tomorrow's technology. The process has already taken an irreversible first step. The first wave has already hit the marketplace. They are "read only" non-erasable laser readable disks. Japanese makers have produced disks in 12-inch and smaller 45-rpm sizes. They use a technology that is the same for video disks as for the "CD" or compact disks that are very popular. Two types of optical disks will soon be available. One will be called "read only", which is the type that already exists. The other type will be called "write once." The "read only disks are the same as are available now and the output devices will be the same as "CD" devices that are currently being sold for $300 and up.
Until now, two of the largest consumer electronics industries have been inhibited from maturing to their fullest market potential. These industries are being prevented from reaching the next generation in large measure because there is no read/write optical laser disk technology currently available that is both reliable and cost effective.
The video and record industries need to move into the digital age and the digital age is the laser age. Without such a move, they will not be able to inject excitement into their industries. The vinyl analog record has been in the market tool long and nearly every home has one. To revitalize the industry will require a technology so superior that consumers will be motivated to upgrade. The compact laser disk was a first step. With read/write capability, the market effect can move the industry to the next step and take over markets currently enjoyed by both tape and vinyl records.
While the record industry needs laser read/write technology to enhance a sagging market, the computer industry is even more desperately in need of this feature. Storage and retrieval of data is at the very core of the computer revolution. The laser disk may be the key. On 51/4 laser disk could hold approximately 550 megabytes of information which is the equivalent of about 1200 floppy disks or 50 hard disks.
This prediction recognizes a market for the rigid disk type of storage media which gives rise to the need for improvements in the manufacture of rigid disks in such a manner as to minimize production costs, increase production yields, and improve the quality of such storage media.
Conventional techniques of making rigid disk recording media leave much to be desired because of the inherent flaws and defects which remain in the media as the result of the manufacture techniques which are used. A rigid disk recording medium includes a rigid substrate over the faces of which a coating of storage material, such as magnetic or optical material, is placed. Unless the substrate is properly manufactured, these flaws or defects will arise inherently, and control in the manufacture of the substrates to eliminate the flaws and defects is a time consuming, high cost aspect of the overall manufacturing process.
To minimize the flaws in such conventional substrates, several different techniques have been adopted and used, none of which with any great success. Among these techniques is an abrasive machining technique in which an abrasive material of various forms is applied to the faces of a substrate to eliminate the flaws or defects on such faces. Another technique is the so-called lathe-turning or diamond-turning technique where each substrate is rotated about its central axis and subjected to the cutting technique of a diamond tipped tool to smooth the faces and to flatten the same while removing thin layers, oxides and other coatings therefrom. Still a third technique is a electrochemical machining technique which subjects the faces of a rigid substrate to an electrochemical process to clean the faces and make them substantially flat and parallel with each other. The most popular technique adopted and used to date, however, is a combination of the three techniques mentioned above. However, none of the techniques used today are economical or provide a high yield output; thus, serious limitations exist in the manufacture of substrates for rigid disk recording media if it is desired to have a high quality product at minimum cost.
A typical procedure in the manufacture of a substrate for use as the base of a rigid disk recording medium includes the purchase of a disk blank with a roughed inner diameter and outer diameter. The blank is initially directed through a double disk grinder to cause the faces of the blank to become substantially flat and to remove the oxide layer, rolling debris and skin on the faces of the blank. Then, the blank is directed through an edging and chamfer machine to bore the inner and outer peripheries to try to assure that the inner and outer diameters will be substantially within certain tolerances. The blank is then directed through a flat baking oven and subjected to 10 to 12 hours of this oven for annealing purposes. In some cases, this heat treatment occurs two to three times prior to the final finish. The blank is then put into a diamond-turning lathe, and the two faces of the blank are subjected to a reduction step by the diamond tool. After this has occurred, both faces of the blank must then be examined and inspected to assure that it contains no major flaws or defects and is within certain tolerances specified for the manufacture of a rigid disk recording medium. All the foregoing is extremely time consuming and costly and provides a limited yield at best, such as 100 to 125 blanks per hour. Moreover, not all of the flaws and defects associated with the blanks are clearly eliminated; thus, the quality of the resulting product for use as a substrate for a rigid disk recording medium is relatively low and rejections are common everyday occurrences. Flaws and defects found in conventional substrates are random and unpredictable. Their combined effect is to produce substrates as unique as fingerprints, traceable to the machinery and variables that are used to produce them. The mechanical integrity and strength of conventional substrates is questionable at all times and their reliability is relatively low over long periods of time.
Because of the foregoing problems associated with conventional disk media substrates, a need has existed and continues to exist for a high quality rigid disk media substrate for use in data storage technology, including those in the microcomputer and other markets, such as audio, video and laser disk recording, all of which require a substrate of high quality specifications and consistent quality. The present invention satisfies the need for such a high quality rigid disk media substrate.